From dbec1a3dfa5e4ea4d136eff32fdd2b6795e5720c Mon Sep 17 00:00:00 2001
From: Jeff Bezanson <jeff.bezanson@gmail.com>
Date: Thu, 14 Jan 2016 18:16:46 -0500
Subject: [PATCH] serialize pointer- and padding-free objects in one write

fixes #14106
---
 base/serialize.jl | 19 ++++++++++++++-----
 src/alloc.c       |  5 +++++
 2 files changed, 19 insertions(+), 5 deletions(-)

diff --git a/base/serialize.jl b/base/serialize.jl
index 54922d2e86803..0803f7184e12a 100644
--- a/base/serialize.jl
+++ b/base/serialize.jl
@@ -420,11 +420,15 @@ function serialize_any(s::SerializationState, x)
     else
         t.mutable && serialize_cycle(s, x) && return
         serialize_type(s, t)
-        for i in 1:nf
-            if isdefined(x, i)
-                serialize(s, getfield(x, i))
-            else
-                writetag(s.io, UNDEFREF_TAG)
+        if t.pointerfree && ccall(:jl_datatype_haspadding, Cint, (Any,), t)==0
+            write(s.io, pointer_from_objref(x), sizeof(x))
+        else
+            for i in 1:nf
+                if isdefined(x, i)
+                    serialize(s, getfield(x, i))
+                else
+                    writetag(s.io, UNDEFREF_TAG)
+                end
             end
         end
     end
@@ -674,6 +678,11 @@ function deserialize(s::SerializationState, t::DataType)
     end
     if nf == 0
         return ccall(:jl_new_struct, Any, (Any,Any...), t)
+    elseif t.pointerfree && ccall(:jl_datatype_haspadding, Cint, (Any,), t)==0
+        x = ccall(:jl_new_struct_uninit, Any, (Any,), t)
+        a_ = pointer_to_array(convert(Ptr{UInt8},pointer_from_objref(x)), sizeof(t))
+        read!(s.io, a_)
+        return x
     elseif isbits(t)
         if nf == 1
             return ccall(:jl_new_struct, Any, (Any,Any...), t, deserialize(s))
diff --git a/src/alloc.c b/src/alloc.c
index 7ae8d2ebdc1b8..c523740d01b2a 100644
--- a/src/alloc.c
+++ b/src/alloc.c
@@ -237,6 +237,11 @@ JL_DLLEXPORT int jl_field_isdefined(jl_value_t *v, size_t i)
     return 1;
 }
 
+JL_DLLEXPORT int jl_datatype_haspadding(jl_datatype_t *dt)
+{
+    return dt->haspadding;
+}
+
 JL_DLLEXPORT jl_value_t *jl_new_struct(jl_datatype_t *type, ...)
 {
     if (type->instance != NULL) return type->instance;